1. Field of the Invention
This invention relates to blends of aromatic carbonate polymers (resins) with acrylate-styrene-acrylonitrile interpolymers (ASA resins) further blended with certain acrylate copolymer resins for gloss reduction.
2. Brief Description of the Prior Art
Molded products made of thermoplastic polymers (resins) are frequently glossy. For some purposes, this is desirable. However, a matte or non-glossy surface is often preferable for products such as housings for computer terminals, typewriters, miscellaneous electrical appliances and certain automotive parts.
Elimination of gloss by surface embossing has been practiced but requires a separate step and adds cost. Moreover, subsequent abrasion may remove the embossed matte surface and cause the gloss to reappear.
The addition to the resin of a delustering agent such as finely-divided silica, silicate, alumina, or other mineral filler generally has a serious detrimental effect on the physical properties of the molded article, such as impact strength. Attempts to add a polymeric delustering agent also frequently have deleterious effects on physical properties, not only impact strength but also on heat distortion temperature, weathering, light stability, and other important properties.
U.S. Pat. No. 4,460,742 describes delustering additives with a core-shell rubber structure based on alkyl acrylate-styrene copolymers which are partially crosslinked.
Blends of polycarbonates with other thermoplastic resins are well known in the art. For example, blends of polycarbonates with certain ASA resins are disclosed in U.S. Pat. No. 4,148,842 and in Kunststoffe, Vol. 75, pp. 33-35 (1985). However, molding of such blends tend to have glossy surface characteristics. The same difficulties as discussed above are observed when conventional methods of reducing gloss are applied to these blends. It is desired to have a means for reducing the gloss in such blends while maintaining good physical properties such as impact strength, tensile strength, and heat resistance.